In a wireless communication system, a number of radio channels provide a connection between users and a central location, such as a base station or access point. In such a system, the wireless channels are a scarce resource which must typically be shared. In a Code Division Multiple Access (CDMA) system, a number of different channels can be transmitted on a single radio frequency carrier by applying different codes to each signal. However, even in a CDMA system, demand for access to channels is so great that the base station must allocate and switch the channels among multiple users.
Often, a wireless user may be switched on, but not actively sending or receiving data. Accordingly, wireless users may be in an “active” mode, and currently allocated a wireless data traffic channel for sending or receiving data, or in an “idle” mode, and not currently sending or receiving data. An idle user may, for example, have just sent or received a data traffic transmission and is therefore deemed likely to soon request a data traffic channel for further transmissions. A maintenance message may therefore be employed to maintain a user in a synchronized but idle state to facilitate allocation of a wireless traffic channel when needed. When a user requests a channel, the idle state allows the user to be allocated a wireless traffic channel more quickly than for a user who was not being maintained in a synchronized idle state. For more information concerning one way to implement a system, please refer to U.S. Pat. No. 6,222,832, entitled “Fast Acquisition of Traffic Channels for a Highly Variable Data Rate Reverse Link of a CDMA Wireless Communication System,” assigned to Tantivy Communications, Inc., assignee of the present application.
A number of users, therefore, may be maintained in an idle state through a periodic sequence of maintenance messages. In the idle state, the maintenance messages typically provide time tracking and power control, and do not require phase reference information employed when in the active state. Time tracking and power control signaling requires less power than the maintenance messages sent during active data payload transmission. The maintenance messages, however, are typically sent at a similar power level during both the idle and active states. Accordingly, the maintenance messages can increase interference and battery power drain during the idle state.